The present discussion is related to power machines. More particularly, the present discussion is related to providing a propelling force to cause power machines to move. Power machines such as skid steer loaders, tracked vehicles, mini-excavators, utility vehicles, wheel loaders and the like have high utility in construction, landscaping, agriculture, and many other types of applications. Power machines of this type have a power source such as an engine that supplies a power that can cause the power machine to be propelled under the control of an operator. In addition, many power machines of this type utilize tools such as buckets to engage in activities such as earth moving. Digging often involves engaging materials that provide significant resistance, which in turn applies a load onto the power source of the power machine. The applied load can result in reduced performance of the power machine because of loss of power from the power source.